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Time-dependent density functional theory calculations have been performed for the excited states of psoralen, 5-methoxypsoralen, and 8-methoxypsoralen in systems and furan and pyrone monoadducts bonded to a thymine residue. The theoretical assignments to ultraviolet (UV) absorption spectra of isolated systems have been performed. The present calculations have clarified that the excitation energies of the first singlet excited (S1) state of monoadducts are blue-shifted compared with the isolated systems. It is shown that, in particular, the S1 excitation energy of the pyrone monoadduct is significantly blue-shifted and, therefore, the pyrone monoadduct is not excited by UV-A light (300-400 nm), which is used in the photochemotherapy. 相似文献
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177.
Y. Kato E. Miura T. Tachi H. Shiraga H. Nishimura H. Daido M. Yamanaka T. Jitsuno M. Takagi P. R. Herman H. Takabe S. Nakai C. Yamanaka M. H. Key G. J. Tallents S. J. Rose P. T. Rumsby 《Applied physics. B, Lasers and optics》1990,50(4):247-256
Planer stripe and foil targets coated with NaF were irradiated with high intensity 351 nm laser radiation of 130 ps duration. Time-integrated as well as time-resolved measurement of gain on NaXIH at 54.2Å were made. A time-integrated gain of 1.2
–1.1
+0.8
cm–1 and a time-resolved peak gain of 3.2±1.0 cm–1 were obtained. A detailed account of the experimental procedures for determination of gain is given. 相似文献
178.
This study aims at developing a new analytical procedure for U–Th radioactive disequilibrium of carbonate rock samples. The
procedure utilizes commercially available U and Th reagents as spikes for isotope dilution analysis with a multiple-collector
inductively coupled mass spectrometer (MC-ICP-MS). Uranium and thorium in a carbonate sample were purified by Fe-coprecipitation,
anion exchange resin, and U/TEVA resin. Isotopic compositions of purified spiked and unspiked U and Th were measured respectively
for abundance and isotopic analyses. The correction of mass fractionation and the Daly/Faraday gain factor for Th measurements
is carried out with a U standard solution. Accuracy of our method was confirmed by analyses of a coral sample that had been
dated with thermal ionization mass spectrometry (TIMS). Our results indicate that U–Th disequilibrium studies are possible
using easily available U and Th reagents as spikes. 相似文献
179.
Voltammetric response of phenylboronic acid monolayer-modified gold electrode to sugars. 总被引:1,自引:0,他引:1
Shigehiro Takahashi Yoshitomo Kashiwagi Tomonori Hoshi Jun-ichi Anzai 《Analytical sciences》2004,20(5):757-759
The surface of a gold (Au) disk electrode was modified with a self-assembled monolayer consisting of phenylboronic acid moiety to fabricate a voltammetric sensor sensitive to sugars. The modified Au electrode exhibited a voltammetric response to sugars in the presence of Fe(CN)6(3-) ion in the sample solution at neutral pH. The peak current of the cyclic voltammograms decreased depending on the type and concentration of sugars. The dynamic range of the electrode is 3 - 100 mM for glucose and mannose and 1 - 30 mM for fructose. The sugar sensor can be used repeatedly after rinsing in 10 mM acetate buffer (pH 4.5). 相似文献
180.
Iida A Takai K Okabayashi T Misaki T Tanabe Y 《Chemical communications (Cambridge, England)》2005,(25):3171-3173
We have developed a practical crossed Claisen condensation between ketene silyl acetals and methyl esters using catalytic NaOH to obtain alpha-monoalkylated beta-keto esters and inaccessible alpha,alpha-dialkylated beta-keto esters. 相似文献